Measurement reporting

ABSTRACT

A network sends downlink a neighbor frequency list for redirection (with at least one neighbor frequency) for measurement, for example event-triggered measurement. For each frequency in the list which a user equipment UE finds to satisfy one or more criteria, for example event-triggering criteria, the idle-state or semi-idle-state UE then takes a measurement of the neighbor frequency and checks whether the measurement satisfies reporting criteria. The UE sends to its serving cell an indication of the neighbor frequency or frequencies whose measurement meets the reporting criteria, without reporting the measurement, such as in a RRC Connection Request message. The serving cell then redirects the UE to establish a connection on a target frequency selected from the indicated neighbor frequencies, and this redirect may be in a RRC Connection Reject message.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a Continuation of U.S. patent application Ser. No.13/863,936 filed Apr. 16, 2013, which is in turn a Continuation of PCTInternational Patent Application No. PCT/CN2012/079646 filed on Aug. 3,2012, and claims the benefit under 35 U.S.C. §119(a) and 37 CFR §1.55 toUK Patent Application No. 1216293.9 filed on Sep. 12, 2012, the entirecontents of each of which are incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to wireless communicationsystems, methods, devices and computer programs and, more specifically,but not exclusively to measurement reporting of neighborcells/frequencies and related signaling in a wireless radio system.

BACKGROUND

Congestion in cellular radio networks is a continuing concern as boththe number of users and especially the volume of data being handledcontinues to increase. In a typical cell there will be a number of userequipments (UEs) in a connected state with the cell and a number ofother UEs in an idle state. Only those in the connected state can sendand receive user data, those in the idle state listen at prescribedtimes in case there is an incoming call to them, and they also measureand report on neighbor cells so they can be redirected or handed overefficiently as they move across the cell.

Different radio access technologies (RATs) use different terms for theidle and the connected states. For example, the Universal TerrestrialRadio Access (UTRA) has several different states beyond the actual IDLEstate which may be considered as idle or at least semi-idle, includingthe cell forward access channel (CELL-FACH) state (semi-idle), the cellpaging channel state (CELL-PCH) state (semi-idle) and the UTRAregistration area paging channel state (URA-PCH). The common feature ofthese UTRA states is that the UE is not allocated a dedicated channel(DCH) for user traffic. The Evolved Universal Terrestrial Radio Access(E-UTRA) system, sometimes referred to as long term evolution (LTE),terms the UE as being in either an idle mode or a radio resource control(RRC) connected mode. Unless otherwise indicated herein, the terms idle(or semi-idle) state and connected state are used in a generic fashionand not specific to any RAT. When a UE is camped on a cell this alsoindicates it is in an idle or semi-idle state.

When a UE in an idle/semi-idle state attempts to establish a connectionwith a radio network cell such as to place a call or access email orsome social network, the radio network currently has no means by whichto re-direct the UE to instead connect to an alternate frequency.Current radio network procedures require the UE's connection request tobe either rejected outright or accepted. Network operators prefer not toreject connection requests (a RRC Connection Reject message in E-UTRAN),but if the cell is congested that leaves the network only the option ofallowing the UE's requested connection and handing it over soon after toanother frequency. If congestion is too severe this may not be possible,but if it is the process of accepting the UE's connection requestincreases cell congestion on the original congested frequency until theredirection can take place. What is needed is a more effective procedurefor radio networks to carry out load balancing with new connectionrequests.

One technique to handle such overloads was proposed for the UniversalMobile Telecommunication System (UMTS, also UTRA) in document R2-105129which is a change request for 3GPP TS 25.331 (3GPP TSG RAN WG2 Meeting#71; Madrid, Spain; 23-27 Aug. 2010). In this approach the UE sendscapability flags in its RRC Connection Request message to indicate whichfrequency bands the requesting UE supports so the network knows the UE'scapability. Knowing the UE capability is not enough, because the networkneeds to know whether the UE sees this neighbor frequency withsufficient strength and/or quality to connect otherwise the UE might notbe able to establish the connection. While the Measurement Reportmessage for inter-RAT LTE measured results can be reported by a UE inthe CELL-FACH state, it is not clear how these results can be signalledin the LTE idle mode or in the UTRA CELL-PCH/URA-PCH states, so at bestthis appears a partial solution only.

For the E-UTRA system, the inventors are aware of two relevantproposals. Document R2-122553 entitled Network Controlled CELL_FACHMobility (3GPP TSG-RAN WG2 Meeting #77bis; Prague, Czech Republic; 21-25May 2012) includes E-UTRA measured results in an uplink RRC message sothat the radio network can redirect the UE to the measured E-UTRAfrequency. Document R2-122609 notes disadvantages with a priorde-prioritisation request signalled to the UE via a RRC ConnectionReject message and proposes instead to signal re-direction informationvia the RRC Connection Reject message. Some reservations have beenexpressed in that the network will not at that time know the UE'scapabilities and so the re-direction might send the UE to a neighborfrequency it does not support. This does not appear solvable byincluding the UE's measured results of the frequencies of RATs in theUE's RRC Connection Request message, since there appears insufficientspace in this uplink control channel message to do so. The similarconstraint is seen to prevent the UE reporting such results in its CellUpdate message while in the CELL-PCH or URA-PC state.

SUMMARY

In a first embodiment, there is a method for controlling a networkaccess node in a wireless communication system, the method including:

sending downlink a neighbor frequency list for redirection formeasurement, the list including at least one neighbor frequency; and

in response to receiving from a user equipment during transition from anidle or semi-idle state an indication that its measurement of at leastone of the neighbor frequencies in the list meets one or more reportingcriteria, redirecting the user equipment to establish a connection on atarget frequency selected from the at least one of the neighborfrequencies.

In a second embodiment, there is apparatus for controlling a networkaccess node in a wireless communication system, the apparatus includingat least one processor and at least one memory including computerprogram code, the at least one memory and the computer program codebeing configured to, with the at least one processor, cause theapparatus at least to:

send downlink a neighbor frequency list for redirection for measurement,the list including at least one neighbor frequency; and

in response to receiving from a user equipment during transition from anidle or semi-idle state an indication that its measurement of at leastone of the neighbor frequencies in the list meets one or more reportingcriteria, redirect the user equipment to establish a connection on atarget frequency selected from the at least one of the neighborfrequencies.

In a third embodiment, there is a computer program product including anon-transitory computer-readable storage medium having computer readableinstructions stored thereon, the computer readable instructions beingexecutable by a computerized device to cause the computerized device tocontrol a network access node in a wireless communication system to atleast:

send downlink a neighbor frequency list for redirection for measurement,the list including at least one neighbor frequency; and

in response to receiving from a user equipment during transition from anidle or semi-idle state an indication that its measurement of at leastone of the neighbor frequencies in the list meets one or more reportingcriteria, redirect the user equipment to establish a connection on atarget frequency selected from the at least one of the neighborfrequencies.

In a fourth embodiment, there is a method for controlling a userequipment in a wireless communication system, the method including:

for each neighbor frequency in a received neighbor frequency list forredirection whose received signal strength and/or quality meet one, ormore criteria, taking a measurement of the neighbor frequency while theuser equipment is in transition from an idle or semi-idle state;

checking whether the measurement satisfies reporting criteria; and

sending to a serving network access node an indication of the neighborfrequency or frequencies whose measurement meets the reporting criteria,without reporting the measurement.

In a fifth embodiment, there is apparatus for controlling a userequipment in a wireless communication system, the apparatus including atleast one processor and at least one memory including computer programcode, the at least one memory and the computer program code beingconfigured to, with the at least one processor, cause the apparatus atleast to:

for each neighbor frequency in a received neighbor frequency list forredirection whose received signal strength and/or quality meet one ormore criteria, take a measurement of the neighbor frequency while theuser equipment is in transition from an idle or semi-idle state;

check whether the measurement satisfies reporting criteria; and

send to a serving network access node an indication of the neighborfrequency or frequencies whose measurement meets the reporting criteria,without reporting the measurement.

In a sixth embodiment, there is a computer program product including anon-transitory computer-readable storage medium having computer readableinstructions stored thereon, the computer readable instructions beingexecutable by a computerized device to cause the computerized device tocontrol a user equipment in a wireless communication system to at least:

for each neighbor frequency in a received neighbor frequency list forredirection whose received signal strength and/or quality meet one ormore criteria, take a measurement of the neighbor frequency while theuser equipment is in transition from an idle or semi-idle state;

check whether the measurement satisfies reporting criteria; and

send to a serving network access node an indication of the neighborfrequency or frequencies whose measurement meets the reporting criteria,without reporting the measurement.

Further features and advantages will become apparent from the followingdescription of preferred embodiments, given by way of example only,which is made with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram of a UE proximal to two cells which is anexample radio environment in which these teachings can be employed.

FIG. 2 is a logic flow diagram illustrating from the perspective of theUE the operation of a method, and a result of execution of computerprogram instructions embodied on a computer readable memory, forpracticing embodiments of these teachings.

FIG. 3 is a simplified block diagram of a user equipment incommunications with two access nodes of a cellular network, which areexample electronic devices suitable for use in practicing embodiments ofthese teachings.

DETAILED DESCRIPTION

FIG. 1 is a schematic diagram of a UE with two cells which is an exampleradio environment in which these teachings can be employed. Assume theUE 20 is in an idle or semi-idle state while traversing through the cellcontrolled by the serving eNB 22 and listens periodically for pages bythat serving eNB 22 on a first frequency. The UE 20 is moving in thedirection of the arrow toward the neighbor base station 23 which isoperating on a different layer than what the UE 20 is camped on with theserving cell. That different layer may be a neighbor frequency in thesame RAT as the serving eNB 22, or it may be in a different RAT from theserving eNB 22. The first frequency has become congested and theidle/semi-idle-state UE 20 sends to the serving eNB 22 a RRC ConnectionRequest message in order to establish a connection to make a call. Theserving eNB 22 prefers not to congest its first frequency further andwould rather the UE 20 established that RRC connection with the neighborcell 23 on the neighbor frequency.

FIG. 1 is a straightforward deployment so the reader may more clearlyunderstand the teachings herein. In other relevant radio scenarios theneighbor frequency may also be operated by the serving eNB 22, and/orthe neighbor base station 23 may be operating on a different RAT fromthat used between the serving eNB 22 and the UE 20. The neighbor basestation 23 may also be embodied as a remote radio head operated by theserving eNB 22. So as not to foreclose these other possibilities thedescription below teaches in terms of the first and neighborfrequencies, the first frequency being that on which the UE 20 is campedand the neighbor frequency being one on which the UE 20 is not. Forcontext, the serving eNB 22 has congestion on the first frequency andprefers the UE 20 to establish its connection on the second/neighborfrequency. The second/neighbor frequency can be intra-RAT in which caseit is utilized with the same RAT as the first frequency, or it may beinter-RAT in which case it is utilized with a different RAT.

In embodiments, the solution herein to the problem set forth in thebackground section involves the UE 20 making an event-triggeredmeasurement of a neighbor frequency. It is known for a UE in the RRCconnected state to take periodic measurements of neighbor cells providedto the UE in a neighbor cell list. Those periodic measurements are notevent driven as is the case of some embodiments herein. In this case theevent is that the UE 20 in transition from the idle or semi-idle statesees the received signal strength and/or the quality of the neighborfrequency exceeding a threshold. The UE 20 is configured for one or morefrequencies for this event triggered measurement by the network, and ina specific but non-limiting embodiment the UE may use for theevent-driven and redirection oriented measurements the same neighborfrequency list as the network might provide the UE for periodic neighborcell measurements. To maintain a distinction for other embodiments, thelist used for the event driven measurements is termed herein as aneighbor frequency list for redirection. In one embodiment the networklists the relevant one or more neighbor frequencies in its broadcastsystem information. In another embodiment the network configures the UE20 for the relevant neighbor frequency or frequencies via a downlink RRCmessage (point to point).

For whichever of those neighbor frequencies of the neighbor frequencylist for redirection on which the UE is capable of operating, the UE 20will then check whether the received signal strength and/or the qualityof that neighbor frequency exceeds a threshold. More particularly, thereare event criteria which the UE checks are met, for example the receivedsignal strength and/or the quality exceeding a threshold for someminimum time interval. If the event criteria are met for a givenfrequency the UE 20 will then, during transition from an idle orsemi-idle state, take a measurement of that neighbor frequency. Thereare various measurements the UE 20 can take in this case, for examplereference signal received power RSRP, reference signal received qualityRSRQ, and others known in the art for measuring neighbor frequencies.The UE 20 compares its neighbor frequency measurement against themeasurement reporting criteria and reports the results as a flag in anuplink RRC message. The reporting criteria may be a threshold RSRP orRSRQ and some minimum time interval over which the measured resultsexceed the threshold. That minimum time interval is conveniently termedherein as a time to trigger (TTT), and both the threshold and the TTTinterval are known to the UEs. In an embodiment the reporting criteriaare the same used by the RRC Connected UEs to report their neighbor cellmeasurements. But in these teachings the flag does not report themeasured results quantitatively, only the comparison of the measuredresults against the reporting criteria. Being a flag it will require aslittle as only one bit per frequency. For example setting the flag bitto “1” indicates the measurement met the reporting criteria from whichthe serving eNB 22 can recognize that that neighbor frequency is asuitable target to re-direct the UE 20 for establishing its RRCconnection. In one particular but non-limiting embodiment the UE 20reports a bit for each of the frequencies in the neighbor frequency listfor redirection, so the UE 20 will se that flag bit to zero for a) thecorresponding neighbor frequency for which it is not compatible, or b)the corresponding neighbor frequency for which its measurement did notmeet the reporting criteria. From the bit=zero flags the serving eNB 22can recognize which neighbor frequency or frequencies is/are not asuitable target for redirecting the UE 20 to establish its RRCconnection.

In one embodiment the event threshold (or all of the event criteria) issignaled to the UE 20 in the system information or in the downlink RRCmessage with the neighbor frequency list for redirection. In anotherembodiment the event threshold or all the event criteria is hard coded,established in a published radio standard and thus it is not necessaryto signal as both UE 20 and serving eNB 22 know it in advance.

The overall process is first explained with respect to the signalingdiagram of FIG. 2, and after which will be expanded details for exampleimplementations in UTRA and E-UTRA networks. The UE 20 first receivesfrom the network at message 202 in system information (SI) or via an RRCmessage a neighbor frequency list for redirection. This neighborfrequency list for redirection may have only one neighbor frequency ormore than one, and one or more may be inter-RAT or intra-RATfrequencies. As noted above the criteria (or at least the threshold), inthese embodiments event criteria, may also be in this downlink message202.

While FIG. 2 shows the UE 20 in the idle or semi-idle state when itreceives this downlink message 202, that is not necessary; the UE 20 maybegin in a RRC connected state with the serving cell 22 when it listensto the SI or receives the downlink RRC message, and after completing theongoing call go into the idle or semi-idle state. Where the neighborfrequency list for redirection is given in a downlink RRC message, inone embodiment this message is sent soon after the UE 20 becomesestablished with the serving cell.

Having received the downlink signaling 202, the UE 20 will, duringtransition from an idle or semi-idle state, measure signal strengthand/or quality of the neighbor frequencies in the list and check atblock 204 if any meet the event criteria. If any do meet the eventcriteria, the measurement event for that neighbor frequency is triggeredand at block 206 the UE 20 makes the more extensive measurement of therelevant neighbor frequency or frequencies. The UE 20 then checks atblock 208 whether this more extensive measurement of the neighborfrequency meets the measurement reporting criteria, and stores thisinformation in its local memory.

At some time unrelated to the measuring and comparing of blocks 206 and208, the UE 20 needs to establish an RRC connection. This may beUE-initiated, or it may be in response to receiving a page that the UE20 has an incoming call. Immediately the UE 20 consults the comparisonfrom block 208 that it stored in its memory to see which neighborfrequencies meet the reporting criteria.

Now having a need to establish an RRC connection, the UE 20 then signalsat message 210 an uplink RRC message which neighborfrequency/frequencies of the neighbor frequency list for redirectionmeet the reporting criteria. In one embodiment it is convenient tosignal this using frequency-specific flags in the UE's RRC ConnectionRequest message, one flag for each neighbor frequency. The conventionalRRC Connection Request does not have room for full measurement resultsbut these few frequency-specific bits can be added without impactingother signaling protocols.

In the assumed radio environment the first frequency on which the UE 20is camped is congested and so the serving eNB 22 prefers to offload thisnewly requested RRC connection to a neighbor frequency, which that sameeNB 22 might be operating or which might be handled by some neighborbase station 23. The serving eNB 22 will know the congestion status ofother neighbor cells' frequencies via its X2 interface with them (or viaother control interfaces for inter-RAT cells, or via an operations andmaintenance O&M entity). So from among the neighbor frequencies of theneighbor frequency list for redirection which the UE 20 indicated atuplink message 210 meet the measurement reporting criteria, the servingeNB 22 will choose one and signal that target frequency to the UE 20 atmessage 212. It is convenient that this redirect indication be includedin the serving eNB's RRC Connection Reject message to the UE 20.

As with the flags in the uplink RRC message 210, the target cellindication in the downlink RRC message 212 can be as small as a fewbits. For example, it may be signaled as an index to either the wholeneighbor frequency list for redirection that was sent downlink inmessage 202, or an index to the frequencies corresponding to the flagsreported by the UE 20 in uplink message 210 if the implementation doesnot have the UE reporting a flag for each listed frequency (for example,if the UE 20 only sends a flag for those frequencies for which it iscompatible or which meet the reporting criteria).

In another embodiment, the UE reports that the measurement reportingcriteria have been met in a new information element added to either theRRC Connection Request message or in a new uplink RRC message. Thisoption is detailed further below, but still it is not the fullmeasurement results which the UE 20 reports but only whether theneighbor frequency measurement reporting criteria have been met.

Now are detailed some non-limiting implementations for differentRAT-specific scenarios.

E-UTRAN Frequency Redirection in E-UTRAN.

In this scenario the UE 20 is in the idle state in the E-UTRA system andthe serving eNB 22 will re-direct the UE 20 to an intra-RAT neighborfrequency. In an example implementation for this scenario, the servingeNB adds a new measurement configuration in system information block(SIB) 3 or SIB5. This is a more particular implementation of the SIdownlink message 202 of FIG. 2. In another embodiment there is alsoadded a new information element (IE) “E-UTRA frequency information forredirection” in which this new information element is carried in eitheror both of those SIBs. However implemented, this is the neighborfrequency list for redirection which gives the frequencies that the UEtests against the event criteria (block 204 of FIG. 2). Thisimplementation may include signaling the event criteria also in SIB3and/or SIB5, or as above the event criteria may be hard coded andimplied by a 1 bit indication which tells the UE 20 whether or not theevent-triggered measurement reporting is configured or not in the cell.If not signaled or implied by the one bit indication, in anotherembodiment the event criteria is implied by the neighbor frequency listfor redirection that measurement of those frequencies according to theseteachings is enabled. In another embodiment, whether or not thehard-coded event-triggered measurement is configured or not in the cellmay be indicated by one bit per frequency in the neighbor cell list orin the neighbor frequency list for redirection (for example, each bitindicates whether event-triggered measurement for the correspondingfrequency is configured or not), or a separate IE.

Signaling from the UE is changed in this implementation for example byadding a single bit to indicate that the measurement reporting criteriahave been met for at least one of the signaled frequencies. Alternativeto this one-bit flag reporting the results of the measurement againstthe reporting criteria, the UE 20 can signal a new IE to send thesimilar information in the RRC Connection Request message 210 for eachE-UTRA frequency signaled in SIB5. Or instead if a new IE “E-UTRAfrequency information for redirection” is added in SIB3 or SIB5, therewill in an embodiment be one new IE per E-UTRA frequency in the IE“E-UTRA frequency information for redirection”.

In this implementation, the network signals event A4 measurementconfiguration in SIB3 or SIB5, and optionally signals an E-UTRAfrequency information IE, which is measured with the event 4Aconfiguration. Event A4 means when the neighbor frequency becomes betterthan a threshold and the UE 20 checks this at block 204 of FIG. 2. TheUE then measures the E-UTRA frequencies which were signaled in the SIwhile the UE is still in the idle mode, which is block 208 of FIG. 2.

When the UE 20 initiates RRC connection establishment, it indicates acorresponding new IE in the RRC Connection Request message 210 if theevent A4 reporting criteria are met for one of the E-UTRA frequenciessignalled in the SI.

If the UE indicates the new IE in the uplink RRC message, the networkmay trigger a redirection procedure toward the E-UTRAN frequencycorresponding to the new IE in the uplink RRC message.

Inter-RAT Frequency Redirection in E-UTRAN

In this scenario the UE 20 is in the idle state in the E-UTRA system andthe serving eNB 22 will re-direct the UE 20 to an inter-RAT neighborfrequency. In this non-limiting implementation there is added toconventional signaling a new measurement configuration for the inter-RATredirection (and optionally also there is added a new IE “inter RATinformation for redirection”, where the UE 20 measures and reports themeasured results on the RAT) in SIB3, SIB6 for UMTS or SIB7 for GERAN.This may include signaling event criteria, but as above the eventcriteria may be hard coded and implied by a 1 bit indication or someother indication such as a list of frequencies that the measurement isenabled for a frequency (or frequencies). This may be 1 bit perfrequency in the neighbor cell list or in the neighbor frequency list,or a separate IE.

In this implementation, there is also added a new IE in the RRCConnection Request message for each inter-RAT frequency signaled in SIB6or SIB7. Or if a new IE “inter-RAT information for redirection” is addedin SIB3, SIB6 or SIB7, there can be one such new IE per neighborfrequency. Alternatively a single bit can be used to indicate that themeasurement reporting criteria have been met for at least one of thesignaled frequencies.

In this scenario, the network signals event B1 measurement configurationin SIB3, SIB6 or SIB7, and optionally also signals an inter-RATinformation element, which is measured with the event B1 configuration.Event B1 is met when the inter-RAT neighbor becomes better than athreshold for the prescribed time interval. The UE 20 then measures theinter-RAT frequencies signaled in the SI while the UE 20 is in the idlemode.

When the UE 20 initiates RRC connection establishment, it indicates acorresponding new IE in the RRC Connection Request message if the eventB1 reporting criteria are met for one of the inter-RAT frequenciessignaled in the SI. If the UE 20 indicates the new IE in the uplink RRCmessage, then the network may trigger a redirection procedure toward theinter-RAT frequency corresponding to the new the new IE in the uplinkRRC message.

E-UTRAN Frequency Redirection in UMTS.

In this scenario, the UE 20 is in the idle or semi-idle state in theUTRA (UMTS) system and the serving cell (NodeB) 22 will re-direct the UE20 to an inter-RAT neighbor frequency in the E-UTRAN system. For thisnon-limiting implementation, there is added to conventional signaling anew measurement configuration for the redirection (and optionally thereis also added a new IE “E-UTRA frequency information for redirection”,where the UE 20 measures and reports the measured results on theneighbor frequency) in SIB11, SIB11bis, SIB12 or SIB19. This may includesignaling the event criteria, but as with the other non-limitingembodiments the event criteria may be hard coded and implied by aone-bit indication whether it is configured or not in the cell, or bysome other indication such as signaling the neighbor frequency list forredirection, that the event-triggered measurement is enabled for afrequency (or frequencies). This may be one bit per frequency in theneighbor cell list or in the neighbor frequency list, or a separate IE.On the UE side, there is added to conventional signaling a new IE in theRRC Connection Request for each E-UTRA neighbor frequency signaled inSIB19. This new IE may also be added to the Cell Update message butthose messages are only used currently when the UE is in the RRCConnected mode. Or if a new IE “E-UTRA frequency information forredirection” is added in SIB11, SIB11bis, SIB12 or SIB9, there is addedone new IE per each E-UTRA neighbor frequency in the IE “E-UTRAfrequency information for redirection”. Alternatively a single bit canbe used to indicate that the measurement event criteria have been metfor at least one of the signaled frequencies. In one non-limitingembodiment, this is realized by extending the existing “pre-redirectioninformation” IE to indicate a bit that the necessary neighborfrequencies have met the measurement criteria.

In this scenario, the network signals the event 3c measurementconfiguration in SIB11, SIB11bis, SIB12 or SIB19, and optionally signalsthe E-UTRA frequency information, which is measured with the event 3cconfiguration. Event 3c is satisfied when the estimated quality ofanother system is above a certain threshold. The UE 20 then measures theE-UTRA neighbor frequencies signaled in the SI.

When the UE 20 initiates RRC connection establishment, it indicates acorresponding new IE in the RRC Connection Request message if the event3c reporting criteria are met for one of the E-UTRA frequencies in theneighbor frequency list for redirection that is signalled in the SI.

When the UE 20 initiates a cell update procedure, it indicates acorresponding new IE in the Cell Update message if the event 3creporting criteria are met for one of the E-UTRA neighbor frequenciessignaled in the SI. As noted above, the Cell Update message is sent bythe UE 20 in the RRC Connected mode.

If the UE 20 indicates the new IE in the uplink RRC message, then thenetwork may trigger a redirection procedure toward the inter-RATfrequency corresponding to the new IE in the uplink RRC message.

Certain embodiments of these teachings provide a technical effect ofimproving the probability of a successful redirection since the goodquality of the target frequency is guaranteed by the UE measurement, andthe network will not trigger a redirection toward some neighborfrequency that is not supported by the UE. Additionally, the limitedspace in the uplink control channel message is not wasted by unnecessaryinformation.

The elements shown at FIG. 2 for the serving eNB 22 and for the UE 20may be considered as representing a logic flow diagram for thoserespective devices, and further may be considered to represent theoperation of a method, and a result of execution of a computer programstored in a computer readable memory, and a specific manner in whichcomponents of an electronic device such as a UE or network access node(or one or more components thereof) are configured to cause thatelectronic device to operate. The various different steps shown in FIG.2 may also be considered as a plurality of coupled loge circuit elementsconstructed to carry out the associated function(s), or specific resultof strings of computer program code stored in a memory. As was noted,FIG. 2 provides more detailed implementation steps than the generalprinciples set forth by these teachings.

The steps of FIG. 2 and the functions they represent are non-limitingexamples, and may be practiced in various components such as integratedcircuit chips and modules, and that embodiments may be realized in anapparatus that is embodied as an integrated circuit. The integratedcircuit, or circuits, may include circuitry (as well as possiblyfirmware) for embodying at least one or more of a data processor or dataprocessors, a digital signal processor or processors, baseband circuitryand radio frequency circuitry that are configurable so as to operate inaccordance with embodiments.

Reference is now made to FIG. 3 for illustrating a simplified blockdiagram of various electronic devices and apparatus that are suitablefor use in practicing embodiments. In FIG. 3 there is a servingcell/serving network access node 22 such as a base transceiver station(termed a node B in the UTRAN system and an eNodeB in the E-UTRANsystem) which is adapted for communication over a wireless link 21A withan apparatus 20 such as a mobile terminal or UE 20 in the idle state (orin one of the PCH/semi-idle states for UTRAN system case). Theidle/semi-id/semi-idle-state UE 20 may also be listening to and/ormeasuring other cells and so FIG. 3 illustrates the serving cell 22 andalso illustrates another network access node, such as for example aneighbor cell 23, that has a wireless link 21B with the UE 20 over whichthe UE 20 takes measurements as detailed above. The serving cell 22 andthe neighbor cell 23 may each be further communicatively coupled viarespective data and control links 25, 27 to a higher network node 24such as a radio network controller RNC in the case of the UTRAN systemor a mobility management entity/serving gateway MME/S-GW 24 in the caseof the E-UTRAN system. There may be a direct interface between theserving cell 22 and the neighbor cell 23, or if they are in differentRATs they may be connected only via a control link between theirrespective but different high network nodes.

The UE 20 includes processing means such as at least one data processor(DP) 20A, storing means such as at least one computer-readable memory(MEM) 20B storing at least one computer program (PROG) 20C,communicating means such as a transmitter TX 20D and a receiver RX 20Efor bidirectional wireless communications with the serving cell 22 andat least for receiving signals from the neighbor cell 23 via one or moreantennas 20F. Within the memory 20B of the UE 20 but shown separately asreference number 20G is also a computer program for comparing theneighbor cell's signal strength and/or quality against the threshold andfor checking the measured results against the reporting criteria, as isdetailed above in various embodiments.

The serving cell 22 also includes processing means such as at least onedata processor (DP) 22A, storing means such as at least onecomputer-readable memory (MEM) 22B storing at least one computer program(PROG) 22C, and communicating means such as a transmitter TX 22D and areceiver RX 22E for bidirectional wireless communications with itsassociated user devices 20 via one or more antennas 22F and a modem. Theserving cell 22 also has stored in its memory at 22G software to compilethe neighbor frequency list for the redirection and to check the flagsor IEs that the UE 20 reports in its uplink RRC message such as the RRCConnection Request message, as is detailed by example above. In theE-UTRAN case, the serving eNB 22 compiles this list, in the UTRAN casethe serving NodeB 22 gets the list from the higher network node 24 whichis a Radio Network Controller RNC.

The neighbor cell/neighbor network access node 23 is similarlyfunctional with blocks 23A, 23B, 23C, 23D, 23E and 23F, which aresimilar in function to those blocks having a same suffix and describedfor the serving cell/serving network access node 22.

For completeness, the higher network node 24 is also shown to include aDP 24A, and a MEM 24B storing a PROG 24C, and additionally a modem 24Hfor communicating with at least the serving cell 22. In the UTRA system,the higher node (RNC) 24 may be the entity which compiles the neighborfrequency list for redirection and then provides that list to theserving NodeB 22 for storage in its local memory 22B/22G anddistribution to the UE 20. While not particularly illustrated for the UE20 or cells 22, 23, those devices are also assumed to include as part oftheir wireless communicating means a modem which may in one example butnon limiting embodiment be inbuilt on an RF front end chip so as tocarry the respective TX 20D/22D/23D and RX 20E/22E/23E.

At least one of the PROGs 20C, 22C in the UE 20 and in the serving cell22 (and at least for the UTRA case also in the higher network node/RNC24) is assumed to include program instructions that, when executed bythe associated DP 20A, 22A, 24A enable the device to operate inaccordance with embodiments as detailed more fully above. In this regardembodiments may be implemented at least in part by computer softwarestored on the MEM 20B, 22B, 24B which is executable by the DP 20A, 22A,24A of the respective devices 20, 22, 24; or by hardware; or by acombination of tangibly stored software and hardware (and tangiblystored firmware). Electronic devices implementing these aspects ofembodiments need not be the entire UE 20, or serving cell 22, butembodiments may be implemented by one or more components of same such asthe above described tangibly stored software, hardware, firmware and DP,or a system on a chip SOC or an application specific integrated circuitASIC or a digital signal processor DSP or a modem or a subscriberidentity module commonly referred to as a SIM card.

Various embodiments of the UE 20 can include, but are not limited to:cellular terminals/telephones including smartphones; data cards, USBdongles, laptop computers, personal portable digital devices havingwireless communication capabilities including but not limited tolaptop/palmtop/tablet computers, digital cameras and music devices, andInternet appliances.

Various embodiments of the computer readable MEM 20B, 22B, 23B, 24Binclude any data storage technology type which is suitable to the localtechnical environment, including but not limited to semiconductor basedmemory devices, magnetic memory devices and systems, optical memorydevices and systems, fixed memory, removable memory, disc memory, flashmemory, DRAM, SRAM, EEPROM and the like. Various embodiments of the DP20A, 22A, 23A, 24A include but are not limited to general purposecomputers, special purpose computers, microprocessors, digital signalprocessors (DSPs) and multi-core processors.

Various modifications and adaptations to the foregoing embodiments maybecome apparent to those skilled in the relevant arts in view of theforegoing description. While embodiments have been described above inthe context of the E-UTRAN and the UTRAN systems, it should beappreciated that embodiments are not limited for use with only thesetypes of wireless communication system, and that they may be employed inother wireless communication systems such as for example the GSM orGERAN or wideband code division multiple access (WCDMA) version ofUTRAN, as some non-limiting further examples.

Some embodiments are described above in relation to event-triggeredmeasurement, but embodiments may also be applied to non-event-triggeredmeasurement. Embodiments include a method for controlling a networkaccess node in a wireless communication system, the method includingsending downlink a neighbor frequency list for redirection formeasurement, the list including at least one neighbor frequency, and inresponse to receiving from a user equipment during transition from anidle or semi-idle state an indication that its measurement of at leastone of the neighbor frequencies in the list meets one or more reportingcriteria, redirecting the user equipment to establish a connection on atarget frequency selected from the at least one of the neighborfrequencies. Embodiments include a method for controlling a userequipment in a wireless communication system, the method including foreach neighbor frequency in a received neighbor frequency list forredirection whose received signal strength and/or quality meet one ormore criteria, taking a measurement of the neighbor frequency while theuser equipment is in transition from an idle or semi-idle state,checking whether the measurement satisfies reporting criteria, andsending to a serving network access node an indication of the neighborfrequency or frequencies whose measurement meets the reporting criteria,without reporting the measurement. In such embodiments, the method mayinclude sending downlink at least one of at least a threshold of one ormore criteria for including the measurement, a time interval forincluding the measurement, and an indication that the measurement isconfigured. In such embodiments, at least one of a threshold of the oneor more criteria, a time interval of the one or more criteria, and anindication that the measurement is configured, is received in downlinksignaling with the neighbor frequency list for redirection. In suchembodiments, the neighbor frequency list for redirection for measurementmay for example include a neighbor frequency list for redirection forevent-triggered measurement and the method may for example includesending downlink at least one of at least a threshold of one or moreevent criteria for triggering the event-triggered measurement, a timeinterval for triggering the event-triggered measurement, and anindication that the event-triggered measurement is configured.

In embodiments, the phrases “during transition” or “in transition” couldfor example relate to transmission of a RRC connection request ontransition from an idle to a connected (CELL_FACH) state. Inembodiments, the phrases “during transition” or “in transition” couldfor example relate to transmission of a cell update on transition from a“CELL_PCH” state to a “CELL_FACH” state.

The above embodiments are to be understood as illustrative examples.Further embodiments are envisaged. It is to be understood that anyfeature described in relation to any one embodiment may be used alone,or in combination with other features described, and may also be used incombination with one or more features of any other of the embodiments,or any combination of any other of the embodiments. Furthermore,equivalents and modifications not described above may also be employedwithout departing from the scope of the invention, which is defined inthe accompanying claims.

What is claimed is:
 1. A method for controlling a network access node ina wireless communication system, the method comprising: sending downlinka neighbor frequency list for redirection for measurement, the listcomprising at least one neighbor frequency; and in response to receivingfrom a user equipment during transition from an idle or semi-idle statean indication that its measurement of at least one of the neighborfrequencies in the list meets one or more reporting criteria,redirecting the user equipment to establish a connection on a targetfrequency selected from the at least one of the neighbor frequencies. 2.The method according to claim 1, wherein the indication comprises aone-bit flag for each of the neighbor frequencies in the list for whichthe user equipment is compatible, and each one-bit flag indicateswhether the user equipment's measurement of the corresponding neighborfrequency meets the one or reporting criteria, and/or the indication iscontained in an information element which is received in a receivedradio resource control message, and/or the indication is received in aRRC Connection Request message, and the redirecting comprises sending anindication of the target frequency in a RRC Connection Reject message.3. The method according to claim 1, wherein the neighbor frequency listfor redirection is sent downlink in radio resource control signaling orthe neighbor frequency list for redirection is sent downlink in systeminformation.
 4. The method according to claim 3, wherein the neighborfrequency list for redirection is in an information element sentdownlink in at least one system information block or each differentfrequency in the neighbor frequency list for redirection is in adifferent information element sent downlink in at least one systeminformation block.
 5. The method according to claim 1, the methodfurther comprising sending downlink at least one of: at least athreshold of one or more criteria for including the measurement; a timeinterval for including the measurement; and an indication that themeasurement is configured.
 6. The method according to claim 5, whereinthe at least threshold and/or the indication are sent downlink with theneighbor frequency list for redirection.
 7. The method according toclaim 1, wherein the neighbor frequency list for redirection formeasurement comprises a neighbor frequency list for redirection forevent-triggered measurement.
 8. The method according to claim 7, themethod further comprising sending downlink at least one of: at least athreshold of one or more event criteria for triggering theevent-triggered measurement; a time interval for triggering theevent-triggered measurement; and an indication that the event-triggeredmeasurement is configured.
 9. An apparatus for controlling a networkaccess node in a wireless communication system, the apparatus comprisingat least one processor and at least one memory including computerprogram code, the at least one memory and the computer program codebeing configured to, with the at least one processor, cause theapparatus at least to: send downlink a neighbor frequency list forredirection for measurement, the list comprising at least one neighborfrequency; and in response to receiving from a user equipment duringtransition from an idle or semi-idle state an indication that itsmeasurement of at least one of the neighbor frequencies in the listmeets one or more reporting criteria, redirect the user equipment toestablish a connection on a target frequency selected from the at leastone of the neighbor frequencies.
 10. A computer program productcomprising a non-transitory computer-readable storage medium havingcomputer readable instructions stored thereon, the computer readableinstructions being executable by a computerized device to cause thecomputerized device to control a network access node in a wirelesscommunication system to at least: send downlink a neighbor frequencylist for redirection for measurement, the list comprising at least oneneighbor frequency; and in response to receiving from a user equipmentduring transition from an idle or semi-idle state an indication that itsmeasurement of at least one of the neighbor frequencies in the listmeets one or more reporting criteria, redirect the user equipment toestablish a connection on a target frequency selected from the at leastone of the neighbor frequencies.
 11. A method for controlling a userequipment in a wireless communication system, the method comprising: foreach neighbor frequency in a received neighbor frequency list forredirection whose received signal strength and/or quality meet one ormore criteria, taking a measurement of the neighbor frequency while theuser equipment is in transition from an idle or semi-idle state;checking whether the measurement satisfies reporting criteria; andsending to a serving network access node an indication of the neighborfrequency or frequencies whose measurement meets the reporting criteria,without reporting the measurement.
 12. The method according to claim 11,wherein the indication comprises a one-bit flag for each of the neighborfrequencies whose measurement exceeds the reporting criteria, and eachone-bit flag indicates whether the user equipment's measurement of thecorresponding neighbor frequency meets the reporting criteria.
 13. Themethod according to claim 11, wherein the indication is contained in aninformation element which is sent in a radio resource control message,and/or the indication is sent in a RRC Connection Request message, andthe method further comprises, in response to receiving in a RRCConnection Reject message an indication of the target frequency whichwas indicated as having a measurement that meets the reporting criteria,attempting to establish a connection on the target frequency.
 14. Themethod according to claim 11, wherein the neighbor frequency list forredirection is received in downlink radio resource control signaling orthe neighbor frequency list for redirection is received in broadcastsystem information.
 15. The method according to claim 14, wherein theneighbor frequency list for redirection is in an information elementreceived in a system information block or each different frequency inthe neighbor frequency list for redirection is received in a differentinformation element of a system information block.
 16. The methodaccording to claim 11, wherein at least one of a threshold of the one ormore criteria, a time interval of the one or more criteria, and anindication that the measurement is configured, is received in downlinksignaling with the neighbor frequency list for redirection.
 17. Themethod according to claim 11, wherein the one or more criteria compriseevent-triggering criteria.
 18. The method according to claim 17, whereinat least one of a threshold of the event-triggering, a time interval ofthe event-triggering, and an indication that the event-triggeredmeasurement is configured, is received in downlink signaling with theneighbor frequency list for redirection.
 19. An apparatus forcontrolling a user equipment in a wireless communication system, theapparatus comprising at least one processor and at least one memoryincluding computer program code, the at least one memory and thecomputer program code being configured to, with the at least oneprocessor, cause the apparatus at least to: for each neighbor frequencyin a received neighbor frequency list for redirection whose receivedsignal strength and/or quality meet one or more criteria, take ameasurement of the neighbor frequency while the user equipment is intransition from an idle or semi-idle state; check whether themeasurement satisfies reporting criteria; and send to a serving networkaccess node an indication of the neighbor frequency or frequencies whosemeasurement meets the reporting criteria, without reporting themeasurement.
 20. A computer program product comprising a non-transitorycomputer-readable storage medium having computer readable instructionsstored thereon, the computer readable instructions being executable by acomputerized device to cause the computerized device to control a userequipment in a wireless communication system to at least: for eachneighbor frequency in a received neighbor frequency list for redirectionwhose received signal strength and/or quality meet one or more criteria,take a measurement of the neighbor frequency while the user equipment isin transition from an idle or semi-idle state; check whether themeasurement satisfies reporting criteria; and send to a serving networkaccess node an indication of the neighbor frequency or frequencies whosemeasurement meets the reporting criteria, without reporting themeasurement.